Joe Biden, Facebook, N.F.L. Draft: Your Thursday Briefing

We’re covering Joe Biden’s long-awaited campaign announcement, the brewing fight between the White House and Congress, and a potential $5 billion fine for Facebook.

Mr. Biden, 76, is set to offer himself as a moderate and a trustee of former President Barack Obama’s legacy, which he will hope can attract a broad cross-section of voters who want to move on from President Trump. But his long political record is expected to face intense scrutiny, particularly from younger, more progressive Democrats.

Citing the end of the special counsel’s investigation, Mr. Trump said on Wednesday that he had been investigated enough. “These aren’t, like, impartial people,” he said. “The Democrats are trying to win 2020.”

Facebook expects a record penalty

The timing of a potential fine was unclear. Facebook has been in negotiations with the F.T.C. over a financial penalty for claims that the company violated a 2011 privacy consent decree.

American regulators have been criticized as lacking scrutiny of tech giants, even as their European counterparts have moved aggressively against the companies.

Quotable: “This would be a joke of a fine — a two-weeks-of-revenue, parking-ticket-level penalty for destroying democracy,” said Matt Stoller, a fellow at the Open Markets Institute, a think tank that is critical of tech companies’ powers. Facebook had $56 billion in revenue last year.

Sri Lanka faces new threats

Imams in the country are being encouraged to cancel Friday Prayer services after the police said that they had information that Sufi Muslims could be attacked by Islamist extremists. Cardinal Malcolm Ranjith of Colombo, the capital, has suspended services for Roman Catholic worshipers through the weekend.

The American ambassador to Sri Lanka, Alaina Teplitz, said on Wednesday that there were “ongoing terrorist plots,” days after suicide bombers killed more than 350 people at churches and hotels across the country.

If you have 5 minutes, this is worth it

Working in the weed industry

While cannabis is still illegal on a federal level, it’s allowed at least for medical purposes in 33 states. And that’s creating hundreds of thousands of jobs, ranging from farm work to executive positions to “budtenders,” who help customers decide what kind of cannabis they want.

But working in the industry comes with caveats, including stigma and a pay cut.

Here’s what else is happening

North Korea-Russia meeting: The North’s leader,Kim Jong-un, met with President Vladimir Putin in Russia today. Mr. Kim is seeking support for sanctions relief and a gradual approach to nuclear disarmament that the Trump administration opposes.

Measles outbreak: The number of cases has risen to 695 — the highest annual number recorded since 2000, when the disease was declared eliminated in the U.S. The virus mostly has affected families that do not vaccinate their children.

White supremacist’s execution: John William King was put to death in Texas on Wednesday for the murder of James Byrd Jr., who was chained to the back of a pickup truck and dragged to his death in 1998.

Snapshot: Above, the Grand Organ at Notre-Dame in Paris last year. The cathedral’s three primary organists initially feared that the instrument — which has five keyboards and almost 8,000 pipes — had been destroyed in the fire that devastated the building last week, but technicians have confirmed that it is safe.

Late-night comedy: Several of the hosts noted a meeting in which President Trump reportedly asked Twitter’s chief executive why he had been losing followers. “It’s like breaking the news to a child that Santa isn’t real,” Trevor Noah said. “It’s like, ‘Sir, you’re 72 now, so I think you’re old enough to know the truth: @MIKHAIL_62875 isn’t a real person.’”

What we’re watching: This TED Talk by Mariah Gladstone, a member of the Blackfeet Nation. “She’s also a cook with a degree from Columbia,” says our national food correspondent, Kim Severson, “who started a cooking show called ‘Indigikitchen’ to help people remember what food was like before colonization: locavore paleo.”

Now, a break from the news

Listen: In his “Ring” cycle, Wagner uses musical themes to create a world of gods, heroes, dwarves and giants. Here’s how.

Go: With few exceptions, musical comedies today are comedic only in the sense that the protagonist doesn’t croak, and musical only in the sense that he does. The new “Tootsie” is an exception, one of our critics writes.

He-he-helium

In 1869, he published the first recognizable periodic table, arranging the 63 elements then known by increasing atomic number — the total number of protons in an atomic nucleus — and in vertical stacks that corresponded to recurring patterns or properties.

That concise organization revealed and predicted many elemental dynamics, and the table became the foundation for chemistry, nuclear physics and other sciences. The periodic system is considered one of modern science’s most important achievements.

But it can also help to explain the chemistry behind a popular party trick: inhaling helium from a balloon to make your voice sound funny.

Helium is lighter than oxygen, enabling the vibrations of your vocal cords to travel more quickly, which shifts the resonant frequencies in your vocal tract to the higher end.

That’s it for this briefing. See you next time.

— Chris

Thank youTo Mark Josephson, Eleanor Stanford, Chris Harcum and Kenneth R. Rosen for the break from the news. Katie Van Syckle wrote today’s Back Story. You can reach the team at briefing@nytimes.com.

P.S.• We’re listening to “The Daily.” Today’s episode is about accusations against a Navy SEAL leader.• Here’s today’s mini crossword puzzle, and a clue: Operator of the world’s largest cargo airline (5 letters). You can find all our puzzles here. • “Caliphate,” a Times podcast series that followed our reporter Rukmini Callimachi’s work on the Islamic State, won a 2018 Peabody Award.